A ring topology network is a high bandwidth, high speed, low latency network configured as a ring which includes a plurality of nodes, each of which is coupled to two adjacent nodes. One node is designated as a master node which coordinates traffic on the network, the remaining N nodes are designated as slave nodes. It will be understood that the “first” and “last” slave nodes are both coupled to the master to complete the ring. FIG. 1 schematically illustrates a ring network 100. Although a network may, of course, include any number of nodes, for clarity and ease of description, the network 100 was chosen to include a master node 102 and N=3 slave nodes 104A, 104B, and 104C. It will be appreciated that the invention claimed herein is not limited to being incorporated into a network of any particular size. Adjacent nodes are coupled or interconnected by ring segments 106A, 106B, 106C and 106D which may comprise both data and clock lines.
A ring network may be employed to distribute uncompressed, real-time, single- or multiple-channel digital audio, clocking and control data to/from various audio and control devices. Audio sources, signal processing, amplification and sound projection may be distributed throughout a facility, all interconnected by electrical or optical cabling. Thus, any (single or multiple) audio input may be routed to any (single or multiple) audio output with each input and each output being capable of being processed and amplified individually.
Within each node on the network is a sample clock running synchronously relative to the clocks of the other nodes. Each ring segment 106 includes half-duplex, bi-directional path on which a clock signal 200 (FIG. 2) originating with the master node 102 is routed to each slave node 104. Additionally, the ring segments 106 include a full-duplex, bi-directional data path 110. In an audio environment, audio data is transferred between nodes along the data path 110. Referring to FIG. 2, the data transfer is initiated by a sample clock edge 202 and must be completed by the next sample clock edge 204. Thus, the full bandwidth extends between two sequential sample clock edges and in an ideal network without any propagation delay, a clock signal could be transmitted instantly to each slave node, thus ensuring perfect clock synchronism and properly timed audio output signals.
However, due to the physical length of each ring segment, a propagation delay occurs in each segment, thereby skewing each slave node's sample clock signal relative to the master clock signal 200. Such skewing is illustrated in FIG. 2 in which the clock signal from the first slave node 104A is represented by the signal 210, the clock signal from the second slave node 104B is represented by the signal 220 and the clock signal from the third slave node 104C is represented by the signal 230. The result of the skewing over the entire network is a reduction of the usable bandwidth 240 to that which extends between the first clock edge 232 of the third slave clock signal 230 and the next clock edge 204 of the master clock signal 200. The remaining “bandwidth” 250 is unusable.
Consequently, there is a need for improving the usable bandwidth in a ring topology network.